Actually, I think one of the big issues with a bat-jam-dao is whether you can use the tip or not. For example, wing chun has some thrusts, but the commercially available butterfly swords are built so that the tip isn't in line with the hilt, making a thrust less efficient.
Given what Gav has shown (and what I've seen elswhere) there's a whole family of these blades, and some are more optimized for chopping, some for stabbing, some for both.
It's important to remember that, especially in later generations of a kung fu school, the moves being taught might not be optimal for the blades being used. The thrusts I mentioned above are but one of a great many examples. In other words, don't assume that the form of a school is perfectly aligned with the blades they currently use to demonstrate that form.
Best,
F
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